Case Study: The Winstone Aggregates Problem

Submitted: 10 Mar 2008

Operations Research Topics: LinearProgramming, BlendingModels

Application Areas:

Contents

• Problem Description

Problem Description

Winstone Aggregates NZ is New Zealand's largest aggregate company. They operate 12 hard rock quarries throughout New Zealand along with Sand Plants, Gravel and Shingle Plants and a Scoria Pit. The aggregates produced by Winstones are used in the construction of roads and buildings. In 1997 Winstone Aggregates approached the Department of Engineering Science (University of Auckland) to help with strategic planning for the closure of the Lunn Ave Quarry in Mt Wellington.

The original model devised by Department of Engineering Science researchers was written in GAMS (General Algebraic Modeling language), and solved using MINOS.

Winstones take Sand, Scoria, Basalt and Greywacke from their quarries and mix these to produce several different types of aggregate:

• Coarse
• Fines
• LowBase
• HighBase
• Sand
• Scalpings
• Scoria
• Sealchips

The amount of each raw material available is limited as the Resource Consent Act controls the extraction of the raw materials from the quarries.

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